The present invention relates to optical time domain reflectometer loss measurements, and more particularly to a method of wavelength normalization of fiber-optic loss measurements so that the accuracy of the loss measurement at a specified optical wavelength is enhanced.
In optical time domain reflectometry a laser transmits an optical pulse into an optical fiber being tested. The Rayleigh backscatter, reflections and losses from the fiber in response to the optical pulse are detected, analyzed and displayed in order to characterize and detect faults in the fiber. For economic reasons the laser has specifications that are looser than those generally required by an end user. Or the wavelength specified by one end user for loss measurements may differ from that specified by another end user by a slight amount. In order to accommodate end user specification of wavelength for loss measurements, either an expensive, highly accurate wavelength laser for each specified measurement wavelength, or the acceptance by the end user of a greater error range in the resulting loss measurement, is required.
What is desired is a wavelength normalization technique for fiber-optic loss measurements that does not require expensive lasers while providing an enhanced loss measurement accuracy for the wavelength specified by the end user.